Experimental investigation to limit the effecting of friction stir welding factors on the strength of AA6061-T651

Abstract

Properties like light weight, high strength-to-weight ratio, and good corrosion resistance make aluminium alloys widely accepted in automotive industry. The low melting point of these alloys makes welding by traditional methods difficult due to the imperfections associated with fusion processes. Friction stir welding (FSW) is a solid-state welding method invented in 1991 at the welding institute (TWI) in the UK; melting and recasting do not occur when using this process. But joints from AA6061-T651 aluminium alloy have been friction stir welded with different welding parameters like tool rotational speed and tool welding speed with constant tool dimension. The effects of rotational and welding speeds on the tensile strength, microhardness distribution and microstructure of the welding joints were studied. The results showed that the maximum tensile strength of the joints can be achieved when using tool with 18 mm and 5 mm shoulder and pin diameter at 710 rpm tool rotational speed and 23 mm/min. Also, we observed that microhardness is markedly affected when tool rotational speed increases.